Method and device for generating a simplified model of a real pair of spectacles

1. A method for generating a simplified geometric model comprising a frame and lenses of a real pair of spectacles, the simplified geometric comprises a predefined number of surfaces and normals thereof, taking as an orientation of these normals an exterior of a convex envelop to the real pair of spectacles, the simplified geometric model been obtained in a phase in which: a set of views of the real pair of spectacles to be modeled is produced, with different angles-of-view and using different screen backgrounds with and without the real pair of spectacles, images of the real pair of spectacles are obtained at high resolution according to V different reference orientations; the simplified geometric model is constructed, consisting of the predefined number of surfaces and their normal beginning with a non-dense surface mesh and using an optimization algorithm that deforms the model's mesh so that projections of its silhouette in each of the views best match the silhouettes detected in the images; and wherein the number V of reference orientations is at least equal to nine.

2. The method according to claim 1 , wherein the predefined number of surfaces of the simplified geometric model is a value close to twenty.

3. The method according to claim 1 , wherein the V*N high-resolution images of the real pair of spectacles are obtained, the lens matching the lens intended for trying on, the real pair of spectacles is photographed at high resolution according to the V different reference orientations and in N light configurations showing the transmission and reflection of the lens of the spectacles, these reference orientations are selected by discretizing a spectrum of orientations corresponding to possible orientations when spectacles are tried on.

4. The method according to claim 3 , wherein an orthogonal reference space with axes x, y, z is defined, where the y-axis corresponds to a vertical axis, ψ to an angle of rotation around the x-axis, φ to an angle of rotation around the y-axis, the V reference orientations selected are such that the angle ψ substantially takes the respective values −16°, 0° or 16°, and the angle φ takes the respective values −16°, 0° or 16°.

5. The method according to claim 4 , further comprising the step of performing a texture calculation using overlays associated to a reference orientation closest to angles φ and ψ, by the following sub-steps: inversion of the normals of each of the surfaces of the pair of spectacles modeled and projection of the frame overlay, limited to the lens space of the reference orientation closest to angles φ and ψ, to obtain a texture overlay of an internal surface of the frame to structure arms of the frame seen through the lens, in a textured reference model, oriented according to the reference orientation closest to angles φ and ψ; projection of the frame overlay, limited to the space outside the lens of the reference orientation closest to angles φ and ψ, to obtain a texture overlay of the external surface of the frame to structure the surfaces of the frame outside the lens, in the textured reference model, oriented according to the reference orientation closest to angles φ and ψ; and projection of the lens overlay limited to the lens to obtain a lens texture overlay to structure the lens, in the textured reference model, oriented according to the reference orientation closest to angles φ and ψ.

6. The method according to claim 3 , wherein: a first light configuration respects colors and materials of the real pair of spectacles, using neutral light conditions, V high-resolution transmission images generated in the first light configuration allow a maximum transmission of light through the lenses to be revealed; and a second light configuration highlights geometric characteristics of the real pair of spectacles using conditions of intense reflection, V high-resolution reflection images obtained in the second light configuration reveal physical reflection properties of the lens.

7. The method according to claim 3 , wherein the phase comprises a step of generating a texture overlay of the frame for each of the V reference orientations.

8. The method according to claim 7 , wherein in the step of generating the texture overlay: for each of the V reference orientations, a high-resolution reflection image is taken, and a binary image is generated with a same resolution as the high-resolution reflection image, the binary image is called the lens silhouette or a binary overlay of the lens and a value of a pixel is equal to one for the pixel representing the lenses and zero otherwise in the lens silhouette.

9. The method according to claim 8 , wherein a shape of the lenses needed to generate the lens silhouette is extracted using an active contours algorithm based on an assumption that the frame and the lenses have different transparencies.

10. The method according to claim 8 , wherein in the step of generating texture overlay: a lens overlay is generated for each of the reference orientations by copying, for each pixel with a value equal to one in the binary overlay of the lens, information contained in the high-resolution reflection image and assigning zero to the other pixels; the lens overlay is a high-definition cropped image of the lens using, for cropping an original high-definition image, the lens silhouette; an associated high-resolution reflection image is selected for each of the reference orientations, and a binary background image is generated by automatically extracting a background; a binary image is generated from a binary overlay of the frame by deducting from a neutral image an outline image of the lenses and an outline image of the background; a texture overlay of the frame behind the lens with a texture of the frame corresponding to a portion of the frame located behind the lenses is generated for each of the reference orientations by copying, for each pixel with a value equal to one in the binary lens overlay, information contained in the high-resolution transmission image, and assigning zero to the other pixels; a texture overlay of the frame outside the lens is generated by copying, for each pixel with a value equal to one in the binary frame overlay, information contained in the high-resolution reflection image, and assigning zero to the other pixels; and an overlay of the texture of the frame is defined as the sum of the overlay of the texture of the frame behind the lens and the overlay of the texture of the frame outside the lens.